Characterization of Lightning Current Measured on Tall Structures

Lightning current waveforms with short rise times have been measured on tall structures such as the CN Tower in Toronto. Those waveforms show multiple reflection of traveling current waves within the tower. They contain information on the transient impedance of the lighting channel and the tower grounding. Numerical electromagnetic analysis using the NEC-2 code is applied to model the electromagnetic response of a tall structure, then the lightning current waveform and the transient impedance of various parts are characterized by comparison with observation.